Field of the Invention
The present invention is directed to a method for transmitting differential pulse code modulated (DPCM) values by data words of different length.
In the transmission of digitized samples, a differential pulse code modulation method is frequently applied for data reduction. The original signal, involving, for example, an audio signal or a video signal, is first converted into an electrical signal, is sampled and is subsequently digitized. Instead of the digitized samples acquired in this manner, only the respective difference of the current sample relative to an estimated value calculated from the preceding samples is transmitted. To this end, the difference referred to as a DPCM value is first quantized and subsequently transmitted as a coded DPCM word. It is known for further data reduction, to take what is referred to an optimal coding, for example, according to Shannon-Fano or Huffman, wherein the frequency of the appearance of individual code words is taken into consideration. The irregular data flow thereby caused requires a considerable circuit expense in the reconstruction of the original samples at the receiver. Moreover, this method is susceptible to disruption given transmission errors and only effects a relatively slight data reduction.